Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
A newer version of this document is available. Customers should click here to go to the newest version.
?lasq4
Computes an approximation to the smallest eigenvalue using values of d from the previous transform. Used by ?bdsqr.
Syntax
call slasq4( i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1, dn2, tau, ttype, g )
call dlasq4( i0, n0, z, pp, n0in, dmin, dmin1, dmin2, dn, dn1, dn2, tau, ttype, g )
Include Files
- mkl.fi
 
Description
The routine computes an approximation tau to the smallest eigenvalue using values of d from the previous transform.
Input Parameters
- i0
 -  
     
INTEGER. First index.
 - n0
 -  
     
INTEGER. Last index.
 - z
 -  
     
REAL for slasq4
DOUBLE PRECISION for dlasq4.
Array, DIMENSION (4n).
z holds the qd array.
 - pp
 -  
     
INTEGER. pp=0 for ping, pp=1 for pong.
 - n0in
 -  
     
INTEGER. The value of n0 at start of eigtest.
 - dmin
 -  
     
REAL for slasq4
DOUBLE PRECISION for dlasq4.
Minimum value of d.
 - dmin1
 -  
     
REAL for slasq4
DOUBLE PRECISION for dlasq4.
Minimum value of d, excluding d(n0).
 - dmin2
 -  
     
REAL for slasq4
DOUBLE PRECISION for dlasq4.
Minimum value of d, excluding d(n0) and d(n0-1).
 - dn
 -  
     
REAL for slasq4
DOUBLE PRECISION for dlasq4. Contains d(n).
 - dn1
 -  
     
REAL for slasq4
DOUBLE PRECISION for dlasq4. Contains d(n-1).
 - dn2
 -  
     
REAL for slasq4
DOUBLE PRECISION for dlasq4. Contains d(n-2).
 - g
 -  
     
REAL for slasq4
DOUBLE PRECISION for dlasq4.
A scalar passed as an argument in order to save its value between calls to ?lasq4.
 
Output Parameters
- tau
 -  
     
REAL for slasq4
DOUBLE PRECISION for dlasq4.
Shift.
 - ttype
 -  
     
INTEGER. Shift type.
 - g
 -  
     
REAL for slasq4
DOUBLE PRECISION for dlasq4.
A scalar passed as an argument in order to save its value between calls to ?lasq4.